This invention relates to an apparatus for sequential loading of bars in a rotating part of a machine tool, in particular by means of a pusher.
Loading apparatuses of this kind are well known by the name of xe2x80x9cfeeder,xe2x80x9d and serve the feeding of machine tools with chip removal, these machine tools themselves also being referred to as machining lathes.
Designated by the term xe2x80x9cpusherxe2x80x9d is the active part of the sequential loading apparatus, i.e. a body which, of predetermined diameter, has an end face intended to rest against one of the ends of the bar to be pushed, on the one hand, and, on the other hand, receives the action of a drive element of displacement in translation along an axis aligned approximately with that of the rotating part.
The invention relates in particular to a sequential loading apparatus for bars in a rotating machine part, this apparatus being of the type having a device for alignment, on the axis of rotation of the rotating part, of the longitudinal axis of at least one portion of the bar situated immediately upstream from this rotating part.
In these machines, the rotating part which receives the bar is conventionally designated xe2x80x9cspindle.xe2x80x9d
These alignment devices are intended to ensure and/or perfect the alignment, with the axis of the spindle, of the longitudinal axis of the portion of the bar which is engaged in this spindle.
In this way, in general, the vibrations caused by the deficiency in straightness of the bars do not spread to the spindle of the machine tool, and the deficiencies in machining which would result from these vibrations can thus be prevented.
In effect, the machining lathes make possible the sequential production of rotary parts whose longitudinal dimension corresponds to a portion of the length of a bar of transverse cross-section compatible with that of the pieces to be made.
In precise terms, each piece is made by machining of at least one portion of the end of a bar which is engaged in the spindle, then cutting of this bar, in particular by truncation, in order to isolate the longitudinal portion that has to make up the piece.
After each machining, the bar is translated in the spindle, under the effect of the pusher of the loading apparatus, to allow a new piece to be made, and this continues until the bar is used up.
Afterwards, a new bar is loaded in the spindle, and the machining cycle can begin again.
Conventionally, an alignment device includes two jaws which, having bearing surfaces able to define a cylindrical support around a bar portion, i.e. on a portion of the length of the latter, are supported by a mechanism allowing opposite displacements of these jaws, i.e. displacements bringing about the spacing apart, or the moving closer together, of the said jaws.
The displacement mechanism is connected to a massive support, such as the structure of the sequential loading apparatus.
The mechanism of displacement of the jaws makes it possible to adjust the position of the said jaws as a function of the diameter of the bar intended to be used in the machine tool.
In the alignment devices known to the applicant, the mechanism for displacement of the jaws is controlled by hand, i.e. a person must intervene to adjust the position of the jaws as a function of the diameter of the bar used in the machine tool situated downstream from the device.
Theoretically, this poses no problem, but in practice oversights have been observed that lead to drawbacks, in particular in the form of production stops.
Precisely speaking, in the case of increase in the diameter of the bar, the loading of the slicing machine is prevented because the end of the bar of increased diameter meets the jaws without being able to pass through them, and thus cannot be loaded into the machine.
Likewise, in the case of loading of a bar of smaller diameter than that of the pusher, the complete loading of the bar into the slicing machine is prevented because the end of the pusher encounters the jaws without being able to pass through them and thus cannot push the bar completely into the machine.
Likewise, in the case of reduction of the diameter of the bar, when there is a change in the type of pieces to be manufactured in series, the slicing machine is deprived of the action of the alignment device because the bar of decreased diameter can be loaded into the machine without cooperating with the jaws.
One object of the invention is to obtain a loading apparatus equipped with an alignment device which makes it possible to correct a lack of adjustment in the alignment device.
Another object of the invention is to obtain a loading apparatus equipped with an alignment device which makes it possible to deal with the occurrence of vibrations in the bar loaded in the spindle of the machine.
To this end, the invention has as its subject matter a sequential loading apparatus for bars in a rotating machine part. The apparatus being of the type having a device for alignment, on the axis of rotation of the rotating part, of the end of the bar intended to be engaged there, this apparatus being characterized in particular in that the displacement mechanism includes a drive element and a device for control of this drive element. The drive element is controlled as a function of at least one of the parameters which are; the diameter of the bar to be loaded in the machine tool, the diameter of the pusher in a part capable of being engaged in the jaws and the surpassing of a predetermined threshold for vibrations in the bar.